Generally, a crystalline epoxy resin has a backbone skeleton which is rigid and multi-functional and accordingly, has high heat resistance, so that a crystalline epoxy resin is used in a field requiring the reliability for heat resistance such as the electric and electronic fields.
However, depending on the application such as casting-molding, in some fields, only a liquid composition can be molded, and the use of an epoxy resin which is crystalline is limited to the applications using solid materials such as an application of transfer-molding, so that the application range of a crystalline epoxy resin is limited.
In addition, in the related art, an epoxy resin used in a liquid molding such as casting molding is a liquid epoxy resin, and cannot fully satisfy the requirement of enhancing curing properties such as heat resistance that have been more severely required nowadays in fields such as adhering, casting, sealing, molding and laminating. Thus, there has been a growing requirement for liquefying a crystalline multi-functional epoxy resin imparting curing properties including high heat resistance. On the other hand, there has also been a growing requirement for the stability of a cured product which is cured in a short wavelength range such as a white LED and a blue LED.
For example, there is disclosed an epoxy resin produced by lowering the crystallinity of an epoxy compound having high crystallinity such as tris(2,3-epoxypropyl) isocyanurate through esterifying a part of the epoxy groups of the epoxy compound to liquefy the epoxy compound (see Patent Document 1).
In addition, there is disclosed a modified epoxy resin composition in which inorganic particles such as silica particles are blended with a liquid epoxy resin.
There is disclosed an epoxy resin composition containing a main agent containing an epoxy resin and an inorganic filler and a curing agent in which the inorganic filler contains aluminum hydroxide and silica (Patent Document 2).
There is disclosed a two-component epoxy resin composition containing an A reagent in which an acid anhydride containing as essential components, methyltetrahydrophthalic acid anhydride and methylhexahydrophthalic acid anhydride, a sphere-shaped silica having an average particle diameter of 2 μm or less and an effect accelerator are blended, and a B agent containing an epoxy resin (Patent Document 3).
There is disclosed a resin composition for sealing a semiconductor containing an epoxy resin having a viscosity measured at 80° C. of 5,000 Pa·s or less, a curing agent and silica particles (Patent Document 4).
[Patent Document 1]
    International Publication Pamphlet No. WO 2006/035641[Patent Document 2]    Japanese Patent Application Publication No. JP-A-05-86168[Patent Document 3]    Japanese Patent Application Publication No. JP-A-11-71503[Patent Document 4]    Japanese Patent Application Publication No. JP-A-2005-206664